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Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking (2H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (-10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average Ta and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p

The aim of this study was to examine video-recorded observations of evening family mealtime at home among Mexican American children to help elucidate style of meal service, fathers' and mothers' feeding practices and child's eating behavior. Consistent with guidelines for coding behaviors, we analyzed observational data of evening mealtimes of 71 Mexican American children aged eight to 10 years. Regarding style of meal service, in almost all cases (96%), parents plated the child's food, with more available on the table or counter in 40% of the observations. Mothers almost always served the child (94%). Regarding parental feeding practices, parents used positive involvement in meals (80%), pressure to eat (42%) and restriction of food (9%). Using food as a reward to control behavior was never used by either parent. The majority (75%) of children requested or negotiated to eat less food, or only eat certain items. In Mexican American families, both mothers and fathers play a role in family mealtimes and both use positive involvement in child's meals, and to a lesser extent pressure to eat, with their children aged eight to 10 years. To help reduce the obesity epidemic, intervention strategies are needed, which integrate the family, a plating style of meal and parental feeding practices that promote healthy eating in the home. To reduce obesity among Mexican American children, interventions that focus on parental positive involvement in child's meal and maintenance of home cooked meals could have a positive impact on the entire family.

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested.

BackgroundPhysical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass.ObjectivesA study is presented of the association between FFM and physical activity in relation to age.MethodsIn a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution.ResultsPAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males

Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1-3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response-energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity.

Total daily energy expenditure ("total expenditure") reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. Total expenditure increased with fat-free mass in a power-law manner, with four distinct life stages. Fat-free mass-adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults. These changes shed light on human development and aging and should help shape nutrition and health strategies across the life span.

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (

This study examined parenting styles, parenting practices and family practices that may be associated with weeknight sleep duration among 8- to 10-year-old Mexican American (MA) children. This cross-sectional study of MA children used baseline data from a 2-year cohort study of mother-child pairs (n = 308) with additional data on fathers (n = 166). Children's weeknight sleep duration was accelerometer estimated and averaged for 2 weeknights. Parents reported on their parenting styles and practices regarding food and family food-related practices. Multivariable linear regression analysis was used to examine sleep duration with parenting styles and practices, and family practices, and adjusting for child gender and body mass index. Model 1 included mothers' parenting styles and practices; Model 2 included both mothers' and fathers' parenting styles and practices. Children's average sleep duration was 9.5 (SD = 0.8) hr. Mothers who used pressure to encourage their children to eat and those who used food to control behavior had children with longer sleep duration (β = 0.21, p

Asprosin is a recently discovered fasting-induced hormone that promotes hepatic glucose production. Here we demonstrate that asprosin in the circulation crosses the blood-brain barrier and directly activates orexigenic AgRP+ neurons via a cAMP-dependent pathway. This signaling results in inhibition of downstream anorexigenic proopiomelanocortin (POMC)-positive neurons in a GABA-dependent manner, which then leads to appetite stimulation and a drive to accumulate adiposity and body weight. In humans, a genetic deficiency in asprosin causes a syndrome characterized by low appetite and extreme leanness; this is phenocopied by mice carrying similar mutations and can be fully rescued by asprosin. Furthermore, we found that obese humans and mice had pathologically elevated concentrations of circulating asprosin, and neutralization of asprosin in the blood with a monoclonal antibody reduced appetite and body weight in obese mice, in addition to improving their glycemic profile. Thus, in addition to performing a glucogenic function, asprosin is a centrally acting orexigenic hormone that is a potential therapeutic target in the treatment of both obesity and diabetes.

Mothers' feeding practices are associated with their children's weight status, but little is known about the associations between fathers' feeding practices and children's weight status. Moreover, there is a dearth of research on Latino fathers' feeding practices and children's weight status, even though Latino children suffer some of the highest obesity rates in the U.S. We examined the associations between fathers' feeding practices and child weight status, conditional on mothers' feeding practices, within 174 Mexican American families with children aged 8-10 years. Parents completed the Parental Feeding Practices Questionnaire, which consists of four subscales: positive involvement in child eating, pressure to eat, use of food to control behavior, and restriction of amount of food. To assess child weight status, body mass index (BMI) was calculated and converted to age- and gender-specific percentile scores (BMI z-score). We fit four sets of regression models, one set for each of the four parental feeding practices subscales, with child BMI z-score as the outcome variable. Fathers' pressure to eat (b = -0.20, p = 0.04; 95% CI: -0.39, -0.01) and use of food to control behavior (b = -0.36, p = 0.02; 95% CI: -0.65, -0.07) were associated with lower child BMI z-score, and restriction of amount of food (b = 0.56, p

Short sleep duration is a risk factor for childhood obesity. Mechanisms are unclear, but may involve selection of high carbohydrate foods. This study examined the association between estimated sleep duration and macronutrient intake as percentages of total energy among Mexican American (MA) 9-11 year olds.This cross-sectional study measured diet using two 24-hour recalls and estimated sleep duration using hip-worn accelerometry in MA children (n=247) who were part of a cohort study. Child and maternal anthropometry were obtained; mothers reported on demographic information. Using linear regression, we examined the relationship of sleep duration with energy intake, sugar intake, and the percentage of energy intake from carbohydrates, fat and protein.Children were 47% male; mean age was 10 (SD=0.9) years. Mean sleep duration was 9.6 (SD=0.8) hours; 53% were overweight/obese, with a mean energy intake of 1759 (SD=514) calories. Longer sleep duration was independently associated with a lower percentage of energy intake from carbohydrates (B= -0.22, P< 0.01) and a higher percentage of energy from fat (B=0.19, P< 0.01), driven by the percentage of energy from polyunsaturated fatty acids (PUFA; B=0.17, P< 0.05). No association was found with the intake of energy or total sugars, or the percent of calories from protein.MA children who slept longer consumed diets with a lower percentage of calories from carbohydrates and a higher percentage from fat, especially from PUFA. Short sleep duration may be a risk factor for food cravings that are high in carbohydrate content, and may displace heart-healthy dietary fat, and thereby increase obesity risk among children.

Objective To determine whether parents who prefer a heavier child would underestimate their child's weight more than those who prefer a leaner child. Methods Participants were Mexican-American families (312 mothers, 173 fathers, and 312 children ages 8-10) who were interviewed and had height and weight measurements. Parents reported their preferred child body size and their perceptions of their child's weight. Parents' underestimation of their child's weight was calculated as the standardized difference between parent's perception of their child's weight and the child's body mass index (BMI) z-score. Demographic factors and parental BMI were also assessed. Results Although 50 % of children were overweight or obese, only 11 % of mothers and 10 % of fathers perceived their children as being somewhat or very overweight. Multiple regressions controlling for covariates (parental BMI and child age) showed that parents who preferred a heavier child body size underestimated their children's weight more, compared to those who preferred a leaner child (β for mothers = .13, p

Hepatic glucose release into the circulation is vital for brain function and survival during periods of fasting and is modulated by an array of hormones that precisely regulate plasma glucose levels. We have identified a fasting-induced protein hormone that modulates hepatic glucose release. It is the C-terminal cleavage product of profibrillin, and we name it Asprosin. Asprosin is secreted by white adipose, circulates at nanomolar levels, and is recruited to the liver, where it activates the G protein-cAMP-PKA pathway, resulting in rapid glucose release into the circulation. Humans and mice with insulin resistance show pathologically elevated plasma asprosin, and its loss of function via immunologic or genetic means has a profound glucose- and insulin-lowering effect secondary to reduced hepatic glucose release. Asprosin represents a glucogenic protein hormone, and therapeutically targeting it may be beneficial in type II diabetes and metabolic syndrome.

BackgroundParental feeding practices are thought to influence children's weight status, through children's eating behavior and nutritional intake. However, because most studies have been cross-sectional, the direction of influence is unclear. Moreover, although obesity rates are high among Latino children, few studies of parental feeding practices have focused on this population.MethodsThis 2-year longitudinal study examined mutual influences over time between parental feeding practices and children's weight status, in Mexican American families with children 18 years old at baseline. Mothers (n = 322) and fathers (n = 182) reported on their feeding practices at baseline, 1-year follow-up, and 2-year follow-up. Weight status, defined by waist-height ratio (WHtR) and body mass index (BMI), was ascertained at all assessments. Cross-lagged panel models were used to examine the mutual influences of parental feeding practices and child weight status over time, controlling for covariates.ResultsBoth mothers' and fathers' restriction of food predicted higher subsequent child weight status at Year 1, and for fathers this effect was also found at Year 2. Mothers' and fathers' pressure to eat predicted lower weight status among boys, but not girls, at Year 1. Child weight status also predicted some parental feeding practices: boys' heavier weight predicted mothers' less pressure to eat at Year 1, less use of food to control behavior at Year 2, and greater restriction at Year 2; and girls' heavier weight at Year 1 predicted fathers' less pressure to eat and less positive involvement in child eating at Year 2.ConclusionsThis study provides longitudinal evidence that some parental feeding practices influence Mexican American children's weight status, and that children's weight status also influences some parental feeding practices. Feeding practices of both mothers and fathers were related to children's weight status, underscoring the importance of including fathers in research on parental feeding practices and child obesity.

Purpose: The purposes of this article are to: (a) describe the rationale and development of the Youth Compendium of Physical Activities (Youth Compendium); and (b) discuss the utility of the Youth Compendium for audiences in research, education, community, health care, public health, and the private sector. Methods: The Youth Compendium provides a list of 196 physical activities (PA) categorized by activity types, specific activities, and metabolic costs (youth metabolic equivalents of task [METy]) as measured by indirect calorimetry. The utility of the Youth Compendium was assessed by describing ways in which it can be used by a variety of audiences. Results: Researchers can use METy values to estimate PA levels and determine changes in PA in intervention studies. Educators can ask students to complete PA records to determine time spent in physical activities and to identify health-enhancing activities for classroom PA breaks. Community leaders, parents, and health care professionals can identify activity types that promote healthful behaviors. Public health agencies can use the METy values for surveillance and as a resource to inform progress toward meeting national physical activity guidelines. Applications for the private sector include the use of METy in PA trackers and other applications. Conclusion: The National Collaborative on Childhood Obesity Research Web site presents the Youth Compendium and related materials to facilitate measurement of the energy cost of nearly 200 physical activities in children and youth. The Youth Compendium provides a way to standardize energy costs in children and youth and has application for a wide variety of audiences. [This article reflects the content of Barbara Ainsworth's 2018 C. H. McCloy Lecture. Additional funding for this project was provided by the National Collaborative on Childhood Obesity Research--a public-private partnership among the the National Cancer Institute (NCI), Centers for Disease Control and Prevention (CDC), Robert Wood Johnson Foundation, and the U.S. Department of Agriculture.]

ObjectiveCross-sectional studies show that sleep is related to childhood obesity. We aimed to examine the longitudinal impact of sleep on the risk of obesity in Mexican American children.Design and methodsWe evaluated 229 Mexican American 8-10-year-olds and their mothers at baseline and at 12- and 24-month follow-ups. Sleep duration and anthropometrics were collected. Age- and gender-specific body mass index (BMI) z-scores (BMIz) were calculated based on Centers for Disease Control and Prevention guidelines. Sleep duration was estimated using accelerometry. Children were also categorized as long or short sleepers, using the National Sleep Foundation's recommendation to define adequate sleep duration (10-11 h for 5-12-year-olds). Using linear regressions, we examined whether sleep duration predicted BMIz, waist-to-height ratio (WHtR), and weight gain at 24 months.ResultsChildren were mostly short sleepers (82%). Children who slept less were more likely to have a higher BMIz, WHtR, and weight gain at the 24-month follow-up (β = -0.07, P = 0.01; β = -0.11, P

BackgroundModerate-vigorous physical activity (%MVPA) confers beneficial effects on child musculoskeletal health, cardiovascular fitness, and psychosocial well-being; in contrast, sedentary time (%SED) is emerging as a risk factor for health. This study aimed to identify parental, child and neighborhood factors influencing longitudinal assessments of body mass index (BMI) and activity patterns among Latino children, and to estimate lagged and cross-lagged effects between child BMI, %MVPA and %SED.MethodsA longitudinal design with assessments at baseline, 1 and 2 years follow-up (FU) was used to evaluate the effects of maternal and paternal factors (BMI, age, education level, acculturation, household income and household size), child factors (gender, age, BMI, pubertal status) and neighborhood factors (disorder, victimization) on child BMI, %MVPA and %SED, expressed as a percent of awake time, in 282 Latino children ages 8-10 y and their parents. This study was restricted to families with a mother and biological father or father figure in the child's life.ResultsAcross time, total daily accelerometer counts (p = 0.04) and steps decreased (p = 0.0001), %SED increased (p = 0.0001), and %MVPA decreased (p = 0.02). Moderate lagged effects or tracking was seen for %MVPA and %SED (p = 0.001). %MVPA varied by gender (5.5% higher in boys than girls, p = 0.0001); child age (-0.4% per year, p = 0.03), and child BMI in boys only (-0.22%, p = 0.0002). Negative effects of paternal age, maternal education and maternal changes in BMI on %MVPA also were seen. %SED increased with child age (2.5% higher per year, p = 0.0001). Positive effects of paternal acculturation, maternal change in BMI, paternal age, and negative effects of household size on %SED were observed. A cross-lagged positive effect of BMI at FU1 on %SED at FU2 was observed for boys and girls (p = 0.03). Neighborhood disorder and victimization were not significant predictors of child BMI, %MVPA or %SED.ConclusionThe major child determinants of physical activity (age, gender and BMI) and minor parental influences (maternal BMI and education, paternal age and acculturation) should be considered in designing interventions to promote %MVPA and reduce %SED among Latino children as they approach adolescence.

We know of no studies comparing parent-reported sleep with accelerometer-estimated sleep in their relation to paediatric adiposity. We examined: (i) the reliability of mother-reported sleep compared with accelerometer-estimated sleep; and (ii) the relationship between both sleep measures and child adiposity. The current cross-sectional study included 303 Mexican American mother-child pairs recruited from Kaiser Permanente Northern California. We measured sleep duration using maternal report and accelerometry and child anthropometrics. Concordance between sleep measures was evaluated using the Bland-Altman method. We conducted zero-ordered correlations between mother-reported sleep, accelerometer-estimated sleep and child BMI z-scores (BMIz). Using linear regression, we examined three models to assess child BMIz with mother-reported sleep (model 1), accelerometer-estimated sleep (model 2) and both sleep measures (model 3). Children had an average age of 8.86 years (SD = 0.82). Mothers reported that their child slept 9.81 ± 0.74 h [95% confidence interval (CI): 9.72, 9.89], compared to 9.58 ± 0.71 h (95% CI: 9.50, 9.66) based on accelerometry. Mother-reported sleep and accelerometer-estimated sleep were correlated (r = 0.33, P

ObjectiveTo determine the association of beverage consumption with obesity in Mexican American school-aged children.DesignCross-sectional study using the baseline data from a cohort study. Mothers and children answered questions about the frequency and quantity of the child's consumption of soda, diet soda, other sugar-sweetened beverages, 100% fruit juice, milk and water. The questions were adapted from the Youth/Adolescent FFQ. Children were weighed and measured. Data were collected on the following potential confounders: maternal BMI, household income, maternal education, maternal occupational status, maternal acculturation, child physical activity, child screen time and child fast-food consumption. Logistic regression was used to examine the association between servings (240 ml) of each beverage per week and obesity (BMI ≥ 95th percentile).SettingParticipants were recruited from among enrolees of the Kaiser Permanente Health Plan of Northern California. Data were collected via an in-home assessment.SubjectsMexican American children (n 319) aged 8-10 years.ResultsAmong participants, 20% were overweight and 31% were obese. After controlling for potential confounders, consuming more servings of soda was associated with increased odds of obesity (OR = 1·29; P < 0·001). Consuming more servings of flavoured milk per week was associated with lower odds of obesity (OR = 0·88; P = 0·004). Consumption of other beverages was not associated with obesity in the multivariate model.ConclusionsDiscouraging soda consumption among Mexican American children may help reduce the high obesity rates in this population.

Abstract Background Although obesity rates are high among Latino children, relatively few studies of parental feeding practices have examined Latino families as a separate group. Culturally-based approaches to measurement development can begin to identify parental feeding practices in specific cultural groups. This study used qualitative and quantitative methods to develop and test the Parental Feeding Practices (PFP) Questionnaire for use with Mexican American parents. Items reflected both parent’s use of control over child eating and child-centered feeding practices. Methods In the qualitative phase of the research, 35 Latino parents participated in focus groups. Items for the PFP were developed from focus group discussions, as well as adapted from existing parent feeding practice measures. Cognitive interviews were conducted with 37 adults to evaluate items. In the quantitative phase, mothers and fathers of 174 Mexican American children ages 8–10 completed the PFP and provided demographic information. Anthropometric measures were obtained on family members. Results Confirmatory factor analyses identified four parental feeding practice dimensions: positive involvement in child eating, pressure to eat, use of food to control behavior, and restriction of amount of food. Factorial invariance modeling suggested equivalent factor meaning and item response scaling across mothers and fathers. Mothers and fathers differed somewhat in their use of feeding practices. All four feeding practices were related to child body mass index (BMI) percentiles, for one or both parents. Mothers reporting more positive involvement had children with lower BMI percentiles. Parents using more pressure to eat had children with lower BMI percentiles, while parents using more restriction had children with higher BMI percentiles. Fathers using food to control behavior had children with lower BMI percentiles. Conclusions Results indicate good initial validity and reliability for the PFP. It can be used to increase understanding of parental feeding practices, children’s eating, and obesity among Mexican Americans, a population at high risk of obesity.